Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: joesatch on March 28, 2022, 09:32:33 am
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Mount it inside the chassis to run DC heaters?
https://www.trcelectronics.com/View/Mean-Well/EPS-15-12.shtml?utm_term=&utm_campaign=Shopping+Display&utm_source=adwords&utm_medium=ppc&hsa_acc=9805199880&hsa_cam=164782104&hsa_grp=53831542026&hsa_ad=263629783832&hsa_src=g&hsa_tgt=pla-809221536479&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gclid=CjwKCAjwuYWSBhByEiwAKd_n_qjM-OWgWdDntnYKOYqC0DtbEL3nmWyhzJqHo-jGguaWvztcMNxAfRoC3bgQAvD_BwE (https://www.trcelectronics.com/View/Mean-Well/EPS-15-12.shtml?utm_term=&utm_campaign=Shopping+Display&utm_source=adwords&utm_medium=ppc&hsa_acc=9805199880&hsa_cam=164782104&hsa_grp=53831542026&hsa_ad=263629783832&hsa_src=g&hsa_tgt=pla-809221536479&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gclid=CjwKCAjwuYWSBhByEiwAKd_n_qjM-OWgWdDntnYKOYqC0DtbEL3nmWyhzJqHo-jGguaWvztcMNxAfRoC3bgQAvD_BwE)
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Short answer ; yes
You should use tubes with 12 heater supply , mostly preamp tubes, not 6V6, 6L6...
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It's $8 why wouldn't everyone run one of these? What am i missing?
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It's $8 why wouldn't everyone run one of these? What am i missing?
I don't need need that, my amps are dead quiet with 6,3 vac.
And the recipes or gadgets to build an amp ; sky is the limit
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I suppose if you're building clean amps. Most of my builds are hot rodded 2204 circuits. Maybe i should test one of these. Where would the ground reference go from this? The DC negative to chassis ground?
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I suppose if you're building clean amps. Most of my builds are hot rodded 2204 circuits. Maybe i should test one of these. Where would the ground reference go from this? The DC negative to chassis ground?
Using 12v dc for heaters, you don't need ground,
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And the recipes or gadgets to build an amp ; sky is the limit
Ding Ding Ding - Truth of the day! :icon_biggrin:
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For 12AX7 at 6.3 vac I've always assumed 150mA draw per tube as the standard but for DC to double that to 300mA per tube
Am I correct in assuming at 12vdc the draw per 12ax7 would be approx 150mA?
So this PS should be good for (8) 12ax7 x 150mA = 1.2Amp running 12vdc?
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fwiw;Guessing that's a switching PS module, which should be fine since the switching frequency is typically way above audio....but;
most "external" noises I've come across can be traced back to switching supplies near amps.
might want to load it with something and put it next to a quiet amp and "test" for interference before you wire it into an amp
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It's $8 why wouldn't everyone run one of these? What am i missing?
Input voltage is 85~264VAC, ideally you have a separate secondary winding on your PT in that ballpark that is rated for 1.25A
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For 12AX7 at 6.3 vac I've always assumed 150mA draw per tube as the standard but for DC to double that to 300mA per tube
Am I correct in assuming at 12vdc the draw per 12ax7 would be approx 150mA?
You should check the 12AX7 datasheet before you rely on these numbers.
I don't know why "DC to double that".
The primary reason most folks don't put naked switching supplies inside audio amplifiers is that they radiate crap. You need a metal box around them. You can buy them boxed, but not typically for eight bux.
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+1 with PRR
If Switchmodes were that good, every one would be using them. There are still issues with long term reliability and as PRR pointed "rail cleanliness" and there can be lots of supersonics depending on SMPS design. (Thus the reasons for c-tick Electrical Safety and EMC approvals and whatever the latest is in your country and region)
I am happy to use an encased (and earthed) switchmode power at a slightly higher voltage and post regulate with a 3 Terminal adjustable Regulator.
I use SMPS in "fit for purpose" applications but there are other applications where reliability is paramount and Linear Power supplies are superior and of course simpler. In HIFI tube applications both DC and AC heater supplies have worked well, so maybe there is something going for the KISS principle.
My thoughts :icon_biggrin:
Kind regards
Mirek
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For 12AX7 at 6.3 vac I've always assumed 150mA draw per tube as the standard
12AX7 is 300mA @ 6.3acv/dcv and 150mA for 12acv/dcv.
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I don't know why "DC to double that".
He probably got that from Merlin? :dontknow:
http://www.valvewizard.co.uk/heater.html
I seem to remember Kevin O'Connor saying dc heaters for a 12 _ _ 7 needs 450mA's for each tube. I think it was for charging the smoothing cap? :dontknow:
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Don't even think using switching power supplies in audio devices. They generate much noise like PRR said .
For free you can use the 6.3VAC from your power tranny. With a good lead dress and elevated reference, they re dead quiet. If you absolutely want the preamp tubes to be fed with 12VDC, just build a REGULATED power supply using a LM7812 or other circuit using different transistor type. There are many examples here on this forum.
COLAS
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Mount it inside the chassis to run DC heaters?
https://www.trcelectronics.com/View/Mean-Well/EPS-15-12.shtml (https://www.trcelectronics.com/View/Mean-Well/EPS-15-12.shtml)
The primary reason most folks don't put naked switching supplies inside audio amplifiers is that they radiate crap. You need a metal box around them. ...
There's a reason the cheap ones are cheap.
Instead, Condor has been making linear regulated supplies for many decades. almost 25 years ago, I bought a pair of tube mic preamps from a gentleman who put the power supplies in an external box: a 250vdc supply for the tube plates, and a 12v supply for the heaters. Both by Condor.
Condor 12v 1.7A linear regulated supply (https://www.mouser.com/ProductDetail/Condor-SL-Power/MBB15-15-A?qs=xaTHtLgvzQJa9XYvRXzDtw%3D%3D) ----> $163
For 25 years, mine has been rock-solid & quiet. But it's not the "Mean Well's" lowest-bidder design.
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Not sure why you are re-quoting yourself?
The MeanWells are extremely reliable. I don't think I have seen a dead one ever. By far my favorite computer supply. Better than what Cisco puts in their small network routers.
Switchers are not to be feared. 120V of distorted bass audio is a bigger problem. But more familiar, and easier to identify. Not easier to treat: that's why we have large caps and chokes and still whine about humm/buzzz.
Cheap supplies of any flavor are to be avoided. Re-capping 50/60Hz supplies keeps us busy. Cheap power transformers do burn/smoke within a decade. Yes, the busy switcher designers have lifted "cheap" to new depths.
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this one comes in a metal box so no noise?
https://www.alliedelec.com/product/mean-well/rs-15-12/70069560/ (https://www.alliedelec.com/product/mean-well/rs-15-12/70069560/)
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> this one comes in a metal box so no noise?
Potentially "less" noise.
Heck, it's cute, it's 11 bucks, if it is nasty in a guitar amp you can find a 12V light or something for it.
The "Class B" rating is a sign. This means OK in a home re: messing up your radio and TV reception (from days when we had analog over-the air radio/TV). Class A is office where they don't care about TV(?).